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firmware: Avoid deadlock of usermodehelper lock at shutdown

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When a system goes to reboot/shutdown, it tries to disable the
usermode helper via usermodehelper_disable().  This might be blocked
when a driver tries to load a firmware beforehand and it's stuck by
some reason.  For example, dell_rbu driver loads the firmware in
non-hotplug mode and waits for user-space clearing the loading sysfs
flag.  If user-space doesn't clear the flag, it waits forever, thus
blocks the reboot, too.

As a workaround, in this patch, the firmware class driver registers a
reboot notifier so that it can abort all pending f/w bufs before
issuing usermodehelper_disable().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	drivers/base/firmware_class.c

Change-Id: I7ff6c198cd34090e55845b9d4035b1e5dc86226b
This commit is contained in:
Takashi Iwai
2013-05-22 18:28:38 +02:00
committed by Greg Hackmann
parent 0beec5004c
commit 28cb7116ee
1 changed files with 40 additions and 3 deletions
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43
drivers/base/firmware_class.c
View File

@@ -27,6 +27,7 @@
#include <linux/pm.h>
#include <linux/suspend.h>
#include <linux/syscore_ops.h>
#include <linux/reboot.h>
#include <generated/utsrelease.h>
@@ -130,6 +131,7 @@ struct firmware_buf {
struct page **pages;
int nr_pages;
int page_array_size;
struct list_head pending_list;
#endif
char fw_id[];
};
@@ -171,6 +173,9 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
strcpy(buf->fw_id, fw_name);
buf->fwc = fwc;
init_completion(&buf->completion);
#ifdef CONFIG_FW_LOADER_USER_HELPER
INIT_LIST_HEAD(&buf->pending_list);
#endif
pr_debug("%s: fw-%s buf=%p\n", __func__, fw_name, buf);
@@ -446,10 +451,8 @@ static struct firmware_priv *to_firmware_priv(struct device *dev)
return container_of(dev, struct firmware_priv, dev);
}
static void fw_load_abort(struct firmware_priv *fw_priv)
static void __fw_load_abort(struct firmware_buf *buf)
{
struct firmware_buf *buf = fw_priv->buf;
/*
* There is a small window in which user can write to 'loading'
* between loading done and disappearance of 'loading'
@@ -457,8 +460,16 @@ static void fw_load_abort(struct firmware_priv *fw_priv)
if (test_bit(FW_STATUS_DONE, &buf->status))
return;
list_del_init(&buf->pending_list);
set_bit(FW_STATUS_ABORT, &buf->status);
complete_all(&buf->completion);
}
static void fw_load_abort(struct firmware_priv *fw_priv)
{
struct firmware_buf *buf = fw_priv->buf;
__fw_load_abort(buf);
/* avoid user action after loading abort */
fw_priv->buf = NULL;
@@ -467,6 +478,25 @@ static void fw_load_abort(struct firmware_priv *fw_priv)
#define is_fw_load_aborted(buf) \
test_bit(FW_STATUS_ABORT, &(buf)->status)
static LIST_HEAD(pending_fw_head);
/* reboot notifier for avoid deadlock with usermode_lock */
static int fw_shutdown_notify(struct notifier_block *unused1,
unsigned long unused2, void *unused3)
{
mutex_lock(&fw_lock);
while (!list_empty(&pending_fw_head))
__fw_load_abort(list_first_entry(&pending_fw_head,
struct firmware_buf,
pending_list));
mutex_unlock(&fw_lock);
return NOTIFY_DONE;
}
static struct notifier_block fw_shutdown_nb = {
.notifier_call = fw_shutdown_notify,
};
static ssize_t firmware_timeout_show(struct class *class,
struct class_attribute *attr,
char *buf)
@@ -619,6 +649,7 @@ static ssize_t firmware_loading_store(struct device *dev,
* is completed.
* */
fw_map_pages_buf(fw_buf);
list_del_init(&fw_buf->pending_list);
complete_all(&fw_buf->completion);
break;
}
@@ -868,6 +899,10 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
}
mutex_lock(&fw_lock);
list_add(&buf->pending_list, &pending_fw_head);
mutex_unlock(&fw_lock);
wait_for_completion(&buf->completion);
cancel_delayed_work_sync(&fw_priv->timeout_work);
@@ -1526,6 +1561,7 @@ static int __init firmware_class_init(void)
{
fw_cache_init();
#ifdef CONFIG_FW_LOADER_USER_HELPER
register_reboot_notifier(&fw_shutdown_nb);
return class_register(&firmware_class);
#else
return 0;
@@ -1539,6 +1575,7 @@ static void __exit firmware_class_exit(void)
unregister_pm_notifier(&fw_cache.pm_notify);
#endif
#ifdef CONFIG_FW_LOADER_USER_HELPER
unregister_reboot_notifier(&fw_shutdown_nb);
class_unregister(&firmware_class);
#endif
}